It is highly desirable for tires to have good wet skid resistance, low rolling resistance, and good wear characteristics. It has traditionally been very difficult to improve a tire's wear characteristics without sacrificing its wet skid resistance and traction characteristics. These properties depend, to a great extent, on the dynamic viscoelastic properties of the rubbers utilized in making the tire.
In order to reduce the rolling resistance and to improve the treadwear characteristics of tires, rubbers having a high rebound have traditionally been utilized in making tire tread rubber compounds. On the other hand, in order to increase the wet skid resistance of a tire, rubbers which undergo a large energy loss have generally been utilized in the tire's tread. In order to balance these two viscoelastically inconsistent properties, mixtures of various types of synthetic and natural rubber are normally utilized in tire treads.
Tire treads are sometimes desired to demonstrate excellent grip properties on snowy and icy roads especially at low ambient temperatures. Simultaneously, the tread is required to have low hysteresis at high temperature to promote lower rolling resistance and high hysteresis at low temperature to promote traction on wet roads. To achieve a low stiffness at low temperatures, low hysteresis at high temperature and high hysteresis at low temperature, it is preferable for the tread compounds of snow/ice tires to utilize a blend of low Tg elastomers.